The inventive tool is related to tools such as that shown and described in U.S. Pat. No. 4,105,490.
During the erection and installation of wall board, dry wall, ceilings, and other such surfaces, there are many reasons that joints, holes, or other irregularities appear on the surface of the wall board panel or between abutting edges of wall board panels. For example, these panels are usually 4 feet wide, are installed in edge-to-edge abutment, and held in place by nails or screws. The heads of the nails or screws are recessed into the wall board so that the nail or screw head will not show on the finished wall, and this leaves an irregularity in the wall board surface over each head. The gaps between abutting edges of wall board, as well as cracks, small holes, and sometimes, nicks or gouges caused by the workmen and their tools also create numerous irregularities on the surface of the wall boards.
Regardless of how these various surface discontinuities were formed, they must be filled with a suitable mastic (sometimes called "mud") to give a smooth, plaster-like surface. If the cracks or discontinuities are large enough, tape must be used along with the mastic to give a greater degree of mechanical strength to the surface.
There are various hand-held applicators for applying mastic to smooth the various discontinuities that form doing installation or repair of dry wall or wall board. Typically, the tools are loaded with mastic manually. For example, a mastic pump is inserted into a bucket containing the mastic, and a pump handle is repetitively and manually moved up and down by an operator to force mastic from an outlet on the pump into a reservoir in the drywall taping tool. This is a very tiring, cumbersome procedure for the operator. The manual pumping also loads the drywall tool unevenly, risking either spillage or underfilling. After this cumbersome procedure, the drywall taping tool can only be used until the reservoir is depleted, when it needs to be refilled by the same process again. This frequent interruption makes the job inefficient.
Previous attempts at automating this process of loading mastic into drywall taping tools have been impractical and unsatisfactory. For example, the system of U.S. Pat. No. 4,127,434 has a tank for holding the mastic which must be pressurized in order to function with the applicator. When the mastic tank is empty, it suffers from the same disadvantages as the prior art described previously, namely, that it must be refilled manually. In addition, the required pressurized tank is costly to manufacture, difficult to clean, and cumbersome for the operator to use.
Accordingly, there is a need for an apparatus for applying mastic to dry wall or other selected surfaces which permits the various applicators to be easily, efficiently and continuously supplied with mastic.